How much is a letter worth? When it comes to branding hot cars, BMW says it has invested at least $260.7 million internationally over nearly 30 years promoting its M series.

So it took offense when a Nissan Canada ad campaign used "the M is coming" - with a capital M and a Nissan logo - to advertise the Infiniti M35 and M45.

BMW sued Nissan in Canada's federal court, alleging trademark infringement. It says it fears even aficionados could confuse Nissan and BMW cars.

But BMW has not produced any evidence of harm, the judge noted in denying BMW's request for an injunction to stop the ads.

No proof, no injunction.

The judge, acknowledging the importance of the M cachet to BMW, told the companies the case would be heard as soon as possible, perhaps late this year.